Abstract:

A gas-operated integrated punching device with plate presser, comprising a
tubular containment body closed hermetically at one end by a bottom and
at the opposite end by a head that is perforated for the passage of a
piston-operated plate presser, which performs a translational motion
within the tubular body; the plate presser is crossed coaxially by a
punch, which is jointly connected to the tubular body; a compression and
expansion chamber for pressurized gas is formed between the plate presser
and the bottom, the gas being loaded into the chamber by way of loading
elements inserted in the bottom or in the tubular body; the pressurized
gas pushes the plate presser between two configurations, a first fully
extracted configuration, in which the outer end of the plate presser is
not in contact with a metal plate to be blanked or punched and protrudes
from the head by such a length as to affect the tip of the punch, and a
second configuration, which is at least partly retracted into the tubular
body and in which the outer end of the plate presser is in contact with a
metal plate being worked.

Claims:

1-18. (canceled)

19. A gas-operated integrated punching device with plate presser,
comprising a tubular containment body that is closed hermetically at one
end by a bottom and at the opposite end by a head that is perforated for
the passage of a piston-operated plate presser, which performs a
translational motion within said tubular body, said plate presser being
crossed coaxially by a punch, which is jointly connected to said tubular
body, a compression and expansion chamber for pressurized gas being
formed between said plate presser and said bottom the pressurized gas
being designed to push said plate presser between two configurations, a
first fully extracted configuration, in which an outer end of the plate
presser is not in contact with a metal plate to be blanked or punched and
protrudes from the head by such a length as to affect a tip of the punch,
and a second configuration, which is at least partly retracted into the
tubular body and in which the outer end of the plate presser is in
contact with one metal plate being worked, wherein said gas is loaded
into said chamber by way of loading means inserted in said bottom or in
said tubular body, and in that a tubular guiding portion for the plate
presser and for protecting said punch extends from said bottom toward the
head, the plate presser being shaped so as to slide thereon.

20. The device according to claim 19, wherein said loading means are
constituted by a one-way valve inserted in the bottom.

21. The device according to claim 19, wherein said punch is jointly
connected to the bottom and is fixed thereto by way of reversible fixing
means.

22. The device according to claim 21, wherein said fixing means comprise
an end face of the punch whose shape is such as to prevent its rotation
and which has a larger cross-section than the punch body, said end face
forming a shoulder that is designed to abut against a corresponding
undercut formed in a through hole provided in the bottom and crossed by
said punch, said end face being locked in said hole with reversible
locking means.

23. The device according to claim 22, wherein said reversible locking
means consist of a threaded element to be screwed into a corresponding
complementarily threaded seat formed at the inlet of said hole.

24. The device according to claim 21, wherein said reversible fixing means
are of the type with snap-acting engagement.

25. The device according to claim 19, wherein said piston-operated plate
presser comprises a first annular part, which lies inside the tubular
body and is contoured so as to slide therein, and a second part, which is
also annular, extends from the first part and is designed to protrude
from said head until it surrounds the tip of the punch in the fully
extracted configuration, said first part carrying external sealing means
for sliding on the internal surface of the tubular body, and internal
sealing means for coaxial sliding on the punch.

26. The device according to claim 19, further comprising a tubular
containment body, with a bottom and a head, which is perforated for the
passage of a piston-operated plate presser, the plate presser being able
to slide on a tubular portion for guiding the plate presser and
protecting a punch, said plate presser and said tubular portion being
crossed by the punch, a base flange expanding from said tubular
containment body, said punch being fixed to the bottom and to the tubular
body by way of its end face that has a larger diameter than the rest of
the body of the punch, said end face being locked between said bottom and
a closure plate, to be arranged so as to face said base flange.

27. The device according to claim 26, wherein said closure plate has a
receptacle that is complementarily shaped with respect to the end face of
the punch and is adapted to contain said end face.

28. The device according to claim 26, wherein said end face has a
rotation-preventing flat region.

29. The device according to claim 26, wherein said flange and said closure
plate have corresponding first holes for screws for fixing to a plate
pressing fixture, and second holes for positioning and centering pins.

30. The device according to claim 26, wherein said piston-operated plate
presser is constituted by two separate parts:a first annular part, which
is internal to the tubular body and is contoured to slide therein and has
an annular abutment portion for stopping during ascent against an
extraction-preventing shoulder formed on the internal face of the tubular
body;and a second annular part, which is axially adjacent to the first
part and is designed to protrude from the head so as to surround a tip of
the punch in the fully extracted configuration.

31. The device according to claim 30, wherein said second annular part is
retained within the tubular body by a stop ring, which is inserted in the
head of the tubular body and is adapted to receive by abutment a
corresponding shoulder that expands radially from the second annular
part.

32. The device according to claim 31, wherein said stop ring is designed
to be removed in order to extract the second annular part of the plate
presser.

33. The device according to claim 29, wherein said plate presser, within
the tubular body, between the head and the annular abutment portion, is
surrounded by a rotation-preventing guiding and lubrication band, which
has a double flat region adapted to prevent the rotation of the plate
presser with respect to the tubular body and the punch.

34. The device according to claim 30, wherein said first annular part
bears external sealing and guiding means for sliding on the internal
surface of the tubular body and internal sealing and guiding means for
coaxial sliding on the tubular portion.

35. The device according to claim 30, wherein said first part of the plate
presser has, within a chamber, also an elastic sealing ring, which is
contoured to adhere both to the tubular containment body and to the
tubular guiding portion for the plate presser.

36. The device according to claim 19, wherein said head of the tubular
body is constituted by an annular cover, which is fixed reversibly to a
cylindrical jacket of the tubular body by way of one or more radial grub
screws.

Description:

[0002]Punching or blanking operations, particularly for the
mass-production of metallic components made of metal plate, for example
for the automotive sector or for the electrical household appliance
sector, generally use presses to the sliders of which one or more
punching devices with plate pressers are applied, while corresponding
dies are coupled to the fixed part of such presses; the metal plate to be
worked is rested on such dies, and the punches, by descending, enter such
dies in order to remove material.

[0003]A punching device with plate presser generally comprises a tubular
containment body, which is closed by a bottom at one end and by a head at
the opposite end; such head is perforated for the passage of a
piston-operated plate presser, which performs a translational motion
within such body and is crossed coaxially by a punch, a containment
chamber for elastic pusher means for the plate presser is formed between
such plate presser and such bottom.

[0004]In known punching devices with plate pressers, the elastic means are
constituted either by a metallic helical spring or by an elastomeric
element made of plastics.

[0005]Although these devices are widespread, they have drawbacks, the
first of which is a pressing force generated by the plate presser on the
metal plate that is insufficient to work so-called high-strength metal
plates, i.e., with a very low thickness (for example between 0.2 and 0.5
mm) and made of high-strength steels, characterized by a tensile strength
that is triple that of ordinary structural steels, and with mechanical
properties that depend on phosphorus and manganese silicates, which are
present in small quantities, and on the extremely low carbon content.

[0006]Helical springs, like elastomeric elements, in fact have a
substantially linear compression curve, according to which the thrust
force is zero if compression is nil; therefore, as the compressed helical
spring (or elastomeric element) that pushes against the plate presser
extends, i.e., when the punching device is lifted from the metal plate
that it has just worked, the pressing force on the plate decreases, and
does so in the most delicate situation, when the punch, lifted by the
slider of the press, is made to exit from the punched metal plate,
dragging with it the edges of the generated hole, with consequent
unwanted deformation of such edge with respect to the desired flatness.

[0007]It is instead in this step that the plate presser in fact should
express the maximum pressing force.

[0008]Further, in order to modify the pressing force of a plate presser,
it is only possible to intervene by changing the entire punching device,
since the tubular bodies of the various punching devices are designed to
contain helical springs or elastomeric elements of very specific
dimensions, which when compressed undergo deformations (i.e., expand
diametrically) and therefore are not preset to contain elastic means of
different dimensions to obtain different thrusts.

[0009]For elastomeric elements in particular, the compression length is
limited, since the diametrical deformation is proportional to such
compression length.

[0010]But it is the compression length of the spring that determines the
maximum stroke of the punch in the metal plate, where the length of the
stroke can be decisive in punching metal plates made of steels that are
particularly designed to deform plastically and require a longer stroke
than usual (for example if a stroke of 12-15 mm is needed but the
obtainable stroke is 10 mm).

[0011]Further, plate pressers are currently provided which must be fitted
on known types of punch holder pressing fixtures, so as to adapt to
punches that are already commercially available, and can be fitted on the
corresponding punch holding fixtures by way of reversible snap-acting or
bayonet engagement means, which also are of the known type.

SUMMARY OF THE INVENTION

[0012]The aim of the present invention is to provide a gas-operated
integrated punching device with plate presser that is capable of
obviating the drawbacks revealed by similar devices of a known type.

[0013]Within this aim, an object of the present invention is to provide a
gas-operated integrated punching device provided with a plate presser
that is capable of a higher pressing force, at least when the punch is
lifted, with respect to known devices.

[0014]Another object of the present invention is to provide a gas-operated
integrated punching device with plate presser that allows to obtain
longer punching strokes than known types of device.

[0015]Another object of the present invention is to provide a gas-operated
integrated punching device with plate presser whose dimensions are
comparable to those of known devices.

[0016]Another object of the present invention is to provide a gas-operated
integrated punching device with plate presser that can be equipped also
with known types of punch.

[0017]Another object of the invention is to provide a gas-operated
integrated punching device with plate presser that can be fitted also on
punching or blanking presses of a known type and already in operation.

[0018]Another object of the present invention is to provide a gas-operated
integrated punching device with plate presser that can be manufactured
with known systems and technologies.

[0019]This aim and these and other objects, which will become better
apparent hereinafter, are achieved by a gas-operated integrated punching
device with plate presser, characterized in that it comprises a tubular
containment body that is closed hermetically at one end by a bottom and
at the opposite end by a head that is perforated for the passage of a
piston-operated plate presser, which performs a translational motion
within said tubular body and is crossed coaxially by a punch that is
jointly connected to said tubular body, a compression and expansion
chamber for pressurized gas being formed between said plate presser and
said bottom, said gas being loaded into said chamber by way of loading
means inserted in said bottom or in said tubular body, the pressurized
gas being designed to push said plate presser between two configurations,
a first fully extracted configuration, in which the outer end of the
plate presser is not in contact with a metal plate to be blanked or
punched and protrudes from the head by such a length as to affect the tip
of the punch, and a second configuration, which is at least partly
retracted into the tubular body and in which the outer end of the plate
presser is in contact with a metal plate being worked.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]Further characteristics and advantages of the invention will become
better apparent from the following detailed description of three
preferred but not exclusive embodiments thereof, illustrated by way of
non-limiting example in the accompanying drawings, wherein:

[0021]FIG. 1 is a sectional side view of a device according to the
invention in a first embodiment thereof;

[0022]FIG. 2 is a sectional side view of the device according to the
invention in a second embodiment thereof.

[0023]FIG. 3 is a cutout perspective view of the device according to the
invention in a third embodiment thereof;

[0024]FIG. 4 is a sectional side view of the device according to the
invention in its third embodiment of FIG. 3;

[0025]FIGS. 5 and 6 are views of a particular detail of the device
according to the invention in its third embodiment of FIGS. 3 and 4;

[0026]FIG. 7 is a view of another detail of the device according to the
invention in its third embodiment;

[0027]FIG. 8 is a view of a variation of the third embodiment of the
device according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028]With reference to the figures, a gas-operated integrated punching
device with plate presser according to the invention is generally
designated by the reference numeral 10 in its first embodiment of FIG. 1.

[0029]The punching device 10 comprises a tubular containment body 11,
which is closed hermetically at one end by a bottom 12 and at the
opposite end by a head 14, which is perforated for the passage of a
piston-operated plate presser 15.

[0030]The plate presser 15 is adapted to perform a translational motion
within the tubular body 11.

[0031]The plate presser 15 is crossed coaxially by a punch 16, which is
jointly connected to the bottom 12 and thus to the tubular body 11, which
in turn is jointly connected to the bottom 12.

[0032]Between the plate presser 15 and the bottom 12 there is a
compression and expansion chamber 17 for pressurized gas, which is loaded
therein by way of loading means, of a known type already in use in
spring-damper units, which are inserted in the bottom 12, as in the
exemplary embodiments described here, or in the tubular body 11.

[0033]The pressurized gas, generally nitrogen, is intended to push the
plate presser 15 between two configurations:

[0034]a first fully extracted configuration, in which an outer end 13 of
the plate presser 15 is not in contact with a metal plate 30 to be
blanked or punched, and protrudes from the head 14 for such a length as
to affect a tip 16a of the punch 16,

[0035]and a second configuration, which is at least partly retracted into
the tubular body 11 and in which the outer end 13 of the plate presser 15
is in contact with one metal plate 30 being worked.

[0036]In FIG. 1, the metal plate 30 is shown rested on a die 31, to be
understood as being of a per se known type.

[0037]The loading means are constituted for example by a one-way valve 18
inserted in the bottom 12.

[0038]The punch 16, as mentioned, is jointly connected to the bottom 12
and is fixed to it by way of reversible fixing means.

[0039]Such reversible fixing means comprise an end face 16b of the punch
16 that has a larger cross-section than the punch body and has such a
shape as to prevent its rotation; the end face 16b forms a shoulder
designed to abut against a corresponding undercut 19 that is formed in a
through hole 20 provided in the bottom 12 and crossed by the punch 16.

[0040]The end face 16b is locked in the hole 20 by way of reversible
locking means.

[0041]Such reversible locking means consist of a threaded element 21, to
be screwed into a corresponding complementarily threaded seat 22 that is
formed at the inlet of the hole 20.

[0042]In an alternative embodiment of the invention, not shown for the
sake of simplicity, the reversible fixing means are of the type with snap
engagement, even of a per se known type.

[0043]The piston-operated plate presser 15 comprises a first annular part
15a, which lies inside the tubular body 11 and is contoured so as to
slide therein, and a second part 15b, which also is annular and protrudes
from the first part 15a and is designed to protrude from the head 14
until it surrounds the tip 16a of the punch 16 in the fully extracted
configuration, as shown in FIG. 1.

[0044]The first part 15a supports external sealing means 23 for sliding on
the internal surface of the tubular body 11 and internal sealing means 24
for axial sliding on the punch 16.

[0045]The sealing means 23 and 24 are constituted by elastic sealing
rings, to be understood as being of a known type, or by other similar and
equivalent elements.

[0046]In a second embodiment of the device according to the invention,
shown in FIG. 2 and designated therein by the reference numeral 110, a
tubular guiding portion 125 for the plate presser 115 and for protecting
the punch 116 extends toward the head 114 from the bottom 112.

[0047]In this embodiment, the plate presser 115 is shaped so as to slide
thereon instead of sliding directly on the punch 116 as in the first
embodiment.

[0048]This second embodiment of the device 110 according to the invention
allows to replace the punch 116 without discharging the gas from the
chamber 17 of the device 110.

[0049]A third embodiment is shown in FIGS. 3 and 4.

[0050]The third embodiment of the device according to the invention,
designated by the reference numeral 210, comprises a tubular containment
body 211, with a bottom 212 and a head 214, which is perforated for the
passage of a piston-operated plate presser 215; the plate presser 215 can
slide on a tubular portion 225 for guiding the plate presser 215 and for
protecting a punch 216; the plate presser 215 and the tubular portion 225
are indeed crossed by the punch 216.

[0051]In this third embodiment of the invention, a base flange 235 extends
from the tubular containment body 211.

[0052]The bottom 212 and the tubular portion 225 are monolithic.

[0053]The punch 216 is fixed to the bottom 212 and to the tubular body 211
by way of its end face 216b, which has a larger diameter than the rest of
the body of the punch 216 and is locked between the bottom 212 and a
closure plate 236, to be arranged so as to face the flange 235.

[0054]The closure plate 236 is contoured so as to affect the flange 235
and has a receptacle 237 which is shaped complementarily with respect to
the end face 216b of the punch and is adapted to contain it.

[0055]The end face 216b has a rotation-preventing flat portion 238,
optionally also for punches that are known and commercially available.

[0056]The flange 235 and the closure plate 236 have corresponding first
holes 239, 240 for screws for fixing to a plate pressing fixture and
second holes 241 and 242 for positioning and centering pins.

[0057]In this third embodiment of the device 210 according to the
invention, the piston-operated plate presser 215 is constituted by two
separate parts:

[0058]a first annular part 215a, which is internal to the tubular body 211
and is contoured to slide therein and has an annular abutment portion 244
for stopping during ascent against an extraction-preventing shoulder 245
formed on the internal face of the tubular body 211;

[0059]and a second annular part 215b, which is axially adjacent to the
first part 215a and is designed to protrude from the head 214 so as to
surround the tip 216a of the punch 216 in the fully extracted
configuration.

[0060]The second annular part 215b is retained within the tubular body 211
by a stop ring 246, which is inserted in the head 214 of the tubular body
211 and is adapted to receive by abutment a corresponding shoulder 247
that expands radially from the second annular part 215b.

[0061]This embodiment allows, by removing the stop ring 246, to extract
the second annular part 215b without discharging the gas from the chamber
217, so as to be able to shape the end 213 of the second annular part
215b or replace the second annular part 215b of the plate presser 215
with another one whose end 213 is shaped differently, depending on the
shape and profile of the plate to be punched.

[0062]The plate presser 215, within the tubular body 211, between the head
214 and the annular portion 244, is surrounded by a rotation-preventing
guiding and lubrication band 248, which is shown in FIGS. 3, 4 and 7.

[0063]The rotation-preventing band 248 comprises an annular portion 248a
that has a larger diameter and a portion 248b that has a smaller
diameter; the portions 248a and 248b form a positioning abutment 249 for
abutment against a corresponding shoulder 250 formed within the tubular
body 211.

[0064]The rotation-preventing band 248 also has a double
rotation-preventing flat region, designated in the figures by the
reference numerals 251 for the outer flat region and 252 for the internal
flat region.

[0065]The rotation-preventing band 248 is made of self-lubricating
material.

[0066]The rotation-preventing band 248 is obtained preferably by molding,
but it is understood that it can be obtained also by means of other
processes and production methods.

[0067]The two flat regions 251 and 252 prevent the rotation of the plate
presser 215 with respect to the tubular body 211 and the punch 216.

[0068]The rotation-preventing band 248 is locked to the tubular
containment body 211 by way of one or more grub screws 265, which are
screwed radially through the body 211 until they press against the
rotation-preventing band 248; the rotation-preventing band 248 is to be
understood as being lockable also by way of other similar and equivalent
means and devices.

[0069]The first part 215a and the second part 215b of the plate presser
215 also are associated with each other by way of means adapted to
prevent mutual rotation.

[0070]In this third embodiment of the invention, such means adapted to
prevent the mutual rotation of the two parts 215a and 215b of the plate
presser are constituted by at least one tab 260, which protrudes from one
of the two parts toward the other one, in this case the first part 215a,
and is adapted to enter a corresponding complementarily shaped slot 261
formed on the other part, in this case the second part 215b.

[0071]The first part 215a bears external sealing and guiding means 223 for
sliding on the internal surface of the tubular body 211 and internal
sealing and guiding means 224a and 224b for coaxial sliding on the
tubular portion 225.

[0072]The external sealing and guiding means 223 are constituted by a
first annular guiding band, the internal sealing and guiding means 224a
are constituted by an internal scraper ring, the internal sealing and
guiding means 224b are constituted by a second annular guiding band.

[0073]The first part 215a of the plate presser 215 has, within the chamber
217, also an elastic sealing ring 263, which is contoured to adhere both
to the tubular containment body 211 and to the tubular guiding portion
225 for the plate presser 215.

[0074]Above the rotation-preventing band 248 there is a scraper ring 275
for protecting the band 248.

[0075]In a variation of this third embodiment, shown in FIG. 8 and
designated by the reference numeral 310 therein, the head 314 of the
tubular body 311 is constituted by an annular cover, which is fixed
reversibly to the cylindrical jacket 311a of the tubular body 311 by way
of one or more radial grub screws 368.

[0076]The operation of the punching device 10, 110 and 210 according to
the invention is fully similar to the operation of known types of
punching device.

[0077]The expected advantages are achieved by using pressurized gas, whose
thrust, as occurs with ordinary spring-damper units, allows to obtain a
compression curve (diagram of force as a function of compression) that
has a much lower gradient than the typical compression curves of helical
springs or of the elastomeric elements that are typically used.

[0078]This entails that the punching device 10, 110 and 210 according to
the invention ensures greater thrust, with respect to known devices,
during the steps for approach to the metal plate 30 and for lifting away
from it, on the part of the plate presser 15, 115 and 215.

[0079]In fact, while known devices in these steps have the helical spring
or the elastomeric element practically fully extended or simply
preloaded, and therefore capable of minimal thrust, the punching device
10, 110 and 210 according to the invention is capable of ensuring that
the plate presser 15, 115 and 215 has a pressing force that is adequate
and proportional to the pressure with which the gas is loaded initially
into the chamber 17 and 217.

[0080]The higher the loading pressure of the gas in the device 10, 110,
210 and 310, the greater the minimum pressing force of which the plate
presser 15, 115 and 215 is capable.

[0081]In practice it has been found that the invention thus conceived
solves the intended aim and objects.

[0082]In particular, a gas-operated integrated punching device with plate
presser is provided which is equipped with a plate presser that is
capable of a higher pressing force, at least during punch lifting, with
respect to known devices, particularly for equal dimensions.

[0083]Further, a gas-operated integrated punching device has been provided
which allows to obtain longer punching strokes than known types of
device, by way of the compressibility of the gas, which obviates the
limitations set by the diametrical expansion for the elastomeric elements
and by the packing of coils in an axial direction of the helical springs.

[0084]Moreover, a punching device has been devised which can be provided
with dimensions that are comparable to those of known devices.

[0085]Moreover, a punching device is provided which can be equipped also
with known types of punch.

[0086]Moreover, differently from what is known, such integrated punching
device with plate presser allows the buyer to have at his disposal a
device that is complete and immediately applicable, differently from the
background art, which proposes plate pressers that must be fitted on
punch holder pressing fixtures also of a known type, so as to adapt to
punches that are already commercially available and can be fitted on the
corresponding punch holder fixtures by way of appropriately provided
engagement means, also of a known type.

[0087]Of course, a punching device is provided which can also be fitted on
known types of punching or blanking press that are already in operation.

[0088]Not least, a gas-operated integrated punching device is provided
which has plate presser that can be manufactured with known systems and
technologies.

[0089]The invention thus conceived is susceptible of numerous
modifications and variations, all of which are within the scope of the
appended claims; all the details may further be replaced with other
technically equivalent elements.

[0090]In practice, the materials employed, so long as they are compatible
with the specific use, as well as the dimensions, may be any according to
requirements and to the state of the art.

[0091]The disclosures in Italian Patent Application No. PD2007A000377 from
which this application claims priority are incorporated herein by
reference.

[0092]Where technical features mentioned in any claim are followed by
reference signs, those reference signs have been included for the sole
purpose of increasing the intelligibility of the claims and accordingly
such reference signs do not have any limiting effect on the
interpretation of each element identified by way of example by such
reference signs.